Recently, as the use of inkjet printers of various configurations has spread widely, color inkjet printers that are capable of high-resolution color printing at substantially photographic quality have become popular. In an inkjet printer, a plurality of nozzle heads, each of which having a number (such as 128) of minute nozzles formed in one or a plurality of rows in the sub scanning direction, are mounted in a carriage. A dot pattern is formed on a discharge-target medium by discharging ink droplets from each nozzle, thus recording a desired image. Japanese Patent Application Laid-Open No. 11-334049 discloses a technique of varying the nozzle pitch by causing a movable link to move with respect to a fixed link, to rotate the nozzle heads partly.
In recent years, liquid-crystal displays have become common in personal computers, wordprocessors, copiers, fax machines, mobile phones, and various types of portable terminal. In addition, liquid-crystal displays that are capable of color display have recently been widely adopted. A color filter is used in the color display of a liquid-crystal display. A color filter is formed of a regular dot pattern of fine filter pixels in the three primary colors of light (red (R), green (G), and blue (B)) on a transparent film. The color filter can be formed by a droplet jet patterning device having a configuration similar to that of the above inkjet printer.
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A droplet jet patterning device for manufacturing such a color filter is disclosed in Japanese Patent No. 3,121,226. This device is designed to discharge droplets of the three colors R, G, and B from a plurality of nozzles formed in a nozzle head, to record R, G, and B dot patterns on a glass substrate. The nozzle pitch can be adjusted to be suitably smaller than the actual nozzle pitch in the sub scanning direction by inclining the nozzle head with respect to the sub scanning direction. When the nozzle head is inclined, the discharge timing of each nozzle is made different to align the positions of the recording start edge on the glass substrate. Deviations of each nozzle from the center line of the nozzle array are corrected by controlling the discharge timing.
A droplet jet patterning device for manufacturing a color filter is disclosed in Japanese Patent Application Laid-Open No. 9-300664. In this case, the nozzle head is inclined and also the nozzle head is moved in the sub scanning direction. This device is provided with nozzle heads for the three colors R, G, and B that are formed in a plate. Each nozzle head is held in a state perpendicular to the discharge-target medium. The two ends of each nozzle head are supported in holders, with the holder at one end being connected rotatably to a head mount and the holder at the other end being connected rotatably to a slide member. Each nozzle head is urged toward the head mount side by a coil spring, so that the relative position of each nozzle head with respect to the head mount can be adjusted by using screws. If fine screws for slide members are used to move the slide members in the sub scanning direction, the inclination angle of the nozzle heads with respect to the sub scanning direction can be changed so that the dot pitch can be adjusted in the sub scanning direction.
Organic electroluminescent (EL) displays are gradually becoming practicable as the next generation of displays instead of liquid-crystal displays. An EL substrate for an organic EL display has an anode layer, a hole transport layer, a light-emitting layer, and a cathode layer formed on the surface of a glass substrate, by way of example. Various light-emitting organic compounds corresponding to light-emission colors are used in the light-emitting layer. An organic EL display has a simple configuration and can be made thinner, lighter, and less expensive, and it also has advantage such as little dependency on the angle of viewing and a lower power consumption.
The method of manufacturing an EL substrate for a color organic EL display will be briefly described here. Above an anode layer formed on a glass substrate, droplets for forming a hole transport layer are discharged and are then fixed by heating in a vacuum or an inert gas. Three different types of droplet corresponding to R, G, and B for an EL light-emitting layer are then discharged onto the hole-transport layer to form a regular dot pattern of three colors of light-emitting pixels. After the dot pattern has been heated in a vacuum, a cathode layer is formed over the EL light-emitting layer.
However, the above-described prior art has problems, as described below. First of all, since the inkjet printer of Japanese Patent Application Laid-Open No. 11-334049 has a configuration in which movable links are moved with respect to fixed links to incline the nozzle head itself, it is necessary to combine at least the fixed links, the movable links, and the nozzle head into a head mount to maintain the inclination angle. This configuration is complicated because the movable links move in an arc shape with respect to the fixed links. Therefore, it is difficult to manufacture a nozzle head unit with nozzle heads.
Japanese Patent No. 3,121,226 does not disclose any mechanism for supporting the nozzle head in an inclinable manner with respect to the sub scanning direction and the actuator for causing the rotation of the nozzle head. Japanese Patent No. 3,121,226 does not propose a technique for enabling removal of a plurality of nozzle heads as a nozzle head unit. The center of rotation during the inclination of the nozzle head is also not clear.
Since the droplet jet patterning device of Japanese Patent Application Laid-Open No. 9-300664 is provided with a plate-shaped nozzle head that stands vertically, there are large limitations on the shape of the nozzle head. During maintenance or replacement of the nozzle heads, each nozzle head must be removed from the holders. However, it would be difficult to set the vertical position of the nozzle head precisely when the two ends of the nozzle head can be inserted and removed from above with respect to the holders. If each nozzle head cannot be inserted and removed from above the holders, it is difficult to remove the nozzle head and thus maintainability cannot be ensured.
Moreover, since the center of rotation of each nozzle head is the rotational axis for supporting the holders, if the nozzle heads are partly rotated, all of the nozzles will change positions in both the main scanning direction and the sub scanning direction Y. For that reason, the data processing load is increased during the calculation of the recording drive data and a rotational angle for causing relative movement of the glass substrate with respect to the nozzle heads in the main scanning direction and the sub scanning direction, making it difficult to increase the precision of the pattern formation.
In addition, since the movement of the slide members is done by manually operating fine screws, the maximum inclination angle of the nozzle heads cannot be made so large. Accordingly, the width of variation of the dot pitch is small.
It often happens in the droplet jet patterning device that dots of a specific color (such as R dots) are displaced by a small distance from each of other dots (such as G or B dots) in the sub scanning direction, as shown in FIG. 29(c). In such a case, it is useful if each nozzle head is moved by just a predetermined distance in the sub scanning direction. However, the configuration of Japanese Patent Application Laid-Open No. 9-300664 enables fine movements of each nozzle head only in the lengthwise direction (nozzle array direction) of the nozzle head, making it impossible to move the nozzle head parallel to the sub scanning direction when the nozzle head is inclined with respect to the sub scanning direction. Since the calculation of the amount of fine movement in the sub scanning direction must be based on both the amount of movement due to the tangent screws and the inclination angle of the nozzle heads, the data processing load is increased during the obtaining of the recording drive data and the inclination rotational angle, making it difficult to increase the precision of pattern formation.
Furthermore, since the nozzle heads are returned in a parallel posture to the sub scanning direction and then the positions of the nozzle heads in the sub scanning direction must be minutely adjusted, the operation of the tangent screws is complicated. Since the positions of the tangent screws and the inclination state will vary with the inclination angle of the nozzle heads, a configuration in which the tangent screws are driven automatically would be totally impossible.
Thus an objective of the present invention is to provide a nozzle head holder in which the insertion and removal of nozzle heads is simple, and which enables the simple insertion to and removal from the device itself with the nozzle heads still installed.
Another objective of the present invention is to provide a nozzle head holder in which the rotatable angle of the nozzle heads is large and in which the nozzle heads can be moved parallel to the sub scanning direction, irrespective of the rotation angle of the nozzle heads.
A further objective of the present invention is to provide a droplet jet patterning device in which the above nozzle head holder is installed and a nozzle head that can be installed to such a nozzle head holder.